Photovoltaic power generation systems, often referred to as “solar power systems,” are increasing in popularity as a “clean” or “green” energy source, as an alternative to fossil fuels and other energy sources. A photovoltaic power generation system typically includes an array of photovoltaic (PV) cells, referred to as solar cells, connected in series and/or in parallel. Direct current (DC) from the solar cell array is collected at a number of junction boxes, including combiners and/or recombiners at which multiple lead of like polarity are merged together, and then supplied to a DC-to-AC inverter, and further supplied to a load through a power distribution board.
Due to increasing current and voltage requirements for such systems, UL standards now require fuses or breakers in most systems. These fuses are typically provided in the combiner and/or recombiner boxes, with separate fuses connected to the incoming positive lead from each PV module, and in some cases additional fuses connected to incoming negative leads from each PV module. UL standards specify minimum space requirements for each type of conductor in a solar junction box, including a minimum “bend space” requirement for each type of conductor, to allow sufficient room for ergonomic access by a technician, e.g., for servicing components in the box. For example, UL standards specify a minimum bend space requirement for fuses located in a solar junction box.
Solar system fuses typically have relatively high resistance values, and can thus generate substantial amounts of heat. As a result, the load capacity for solar junction boxes may be limited (e.g., by UL code requirements) to reduce the risk of arcing and/or fire in the boxes. In some systems, the junctions box load capacity acts as a capacity bottleneck for the system. Thus, the heat-generating fuses may limit the load capacity for the entire solar power system.